Kumu

A small, BASIC-inspired programming language built for teaching — with a hand-written interpreter in C++17, a reference manual, and a 17-chapter textbook.

Kumu keeps the friendly parts of BASIC — PRINT, IF, FOR, keywords in capitals — and drops the parts that make it hard to learn from. There are no line numbers and no GOTO. Every block in the language is written exactly one way, a header followed by { ... }, so there is only ever one shape to learn.

# Average a student's scores, and say how they did.

FUNCTION average(scores) {
    VAR total = 0
    FOR EACH s IN scores {
        total = total + s
    }
    RETURN total / scores.LEN()
}

VAR scores = [88, 92, 79, 95]
VAR mean = average(scores)

PRINT "Scores:  " + scores.JOIN(", ")
PRINT "Average: " + mean

IF mean >= 90 {
    PRINT "Grade:   A"
} ELSEIF mean >= 80 {
    PRINT "Grade:   B"
} ELSE {
    PRINT "Grade:   C or below"
}

Scores:  88, 92, 79, 95
Average: 88.5
Grade:   B

Where to start

If you are learning to program, start with the Textbook. It is written to be worked through in order, on your own, with a runnable example for nearly every idea and answers to every exercise in the back.

If you already program and just want the specifics, the Manual is the reference: ten sections covering the full syntax, every built-in, and the precise semantics.

The Goals page explains what Kumu is trying to do and why it is shaped the way it is.

Running it

Kumu needs g++ with C++17 support and make. There are no other dependencies.

git clone https://github.com/justinsloan/kumu-code.git
cd kumu-code
make
./kumu collections.kumu

make produces a single kumu binary. To run your own program, save it with a .kumu extension and pass it in:

./kumu myprogram.kumu

Example programs

The repository ships four programs you can read and run:

Program	What it shows
todo.kumu	A complete to-do manager — due dates, tags, priorities, completion and an archive, sorted any way you like and persisted to todo.csv. The largest program here.
address.kumu	The flagship example — an interactive address book using essentially every feature together, persisting contacts to a CSV file.
collections.kumu	Matrix vs. List: when you want a table and when you want a sequence.
test.kumu	A broad feature sweep, useful as a syntax reference by example.
hello.kumu	A short tour that ends with a deliberate mistake, to show what an error looks like.